It's a good little app, however as with every application/product which claims or is touted to be a
something "Killer" ... it's just not. It can certainly stand on it's own two feet, but it wont be replacing photoshop on desktops across the globe.
I like it, and will likely be using it more and more for smaller image tweaks simply because using photoshop for such things is unnecessary, though for those small tweaks (Rei-sizing, adding text, etc.) I've become quite attached to
Skitch.